A spectator fell to his death from a walkway outside the San Francisco 49ers' stadium over the weekend, while in Indianapolis, two spectators were injured when a railing collapsed inside the Colts' stadium.

"The best thing we can do is to use the occurrence of something as an opportunity to re-asses the safety measures that go on at every large public accommodation," Steve Adelman, an Arizona-based attorney and venue safety expert, told ABCNews.com.

The incidents over the weekend occurred at two very different stadiums, Adelman said.

In San Francisco, Kevin Hayes, 32, fell from a pedestrian walkway while walking to historic Candlestick Park, where the 49ers played their final season opener at the venue on Sunday before moving to a new venue next season. It was not clear how far Hayes fell or what caused him to stumble.

Multiple witnesses told police that Hayes appeared to be intoxicated at the time of his fall, according to ABC News' San Francisco station KGO-TV.

Medics and off-duty police officers administered first aid until an ambulance arrived, at which point Hayes was declared dead from his injuries, KGO reported.

The accident happened the same day two fans were injured when a railing collapsed at the 5-year-old Lucas Oil stadium in Indianapolis where the Colts played the Oakland Raiders.

Stadium officials said it appeared both fans were not seriously injured.

Even though many sports stadiums will respond to accidents with increased safety measures, such as higher railings or safety netting, Alana Penza, program manager for the Institute for the Study of Sports Incidents at the University of Southern Mississippi, said it is difficult to control every fan's behavior.

Since 2003, there have been more than two dozen cases of fans falling at stadiums across the United States, she said, and at least some of the incidents appear to be alcohol related.

"Over the past few years, a lot of the venues have been coming out with fans' codes of conduct," Penza said. "It's another way stadiums are letting fans know their behavior must be appropriate."

Security staff at each stadium may be adept at spotting the subtler signs of intoxication in fans, Adelman said, however he said there is "pressure to get people moving."

"The training is strong, but the countervailing pressure is to move people through the checkpoint so they can get to the game," Adelman said.

The incidents over the weekend came just one month after an Atlanta Braves fan was killed after falling over fourth-level railing at Turner Field in Atlanta and a Denver Broncos fan was injured when he fell 10 feet from an escalator at a pre-season football game.